A plastic lens has been used for various types of optical devices. The plastic lens is required to have excellent optical characteristics depending on purposes of the devices. Further, the plastic lens is required to have high durability, such as heat resistance and weather resistance, and high productivity for molding with high yield according to a use aspect.
As a resin material for the plastic lens, for example, a transparent resin such as a polycarbonate resin, a cycloolefin polymer, an acrylic resin, or a methacrylic resin has been used (Patent Documents 1 and 2).
The plastic lens is used, for example, for a CMOS image sensor or a CCD image sensor that is used for a variety of devices such as a cellular phone, a digital camera, an in-vehicle camera, a surveillance camera, and a security camera. In the image sensors, a decrease in amount of concentrated light per pixel due to microfabrication is prevented by placing a micro lens. For such a lens, a material having transparency and high refractive index is required to improve the light extraction efficiency and light concentrating properties.
In consideration of severe usage environment of an in-vehicle camera and the like, the material is also required to have heat resistance.
In recent years, attention is attracted to a wearable terminal capable of being worn that is new use of the CMOS image sensor.
When for the new use, the image sensor is incorporated into a device or the like, further miniaturization and a reduction in weight and cost are required for the image sensor. Therefore, in the plastic lens used in the image sensor for such a new use, it is desirable that a basic performance such as the transparency, refractive index, and heat resistance is improved to achieve the miniaturization above mentioned and the like of the image sensor. Further, it is desirable to achieve a simple manufacturing process and a reduction in cost as compared with conventional manufacturing using injection molding.